Device, system and method for selective activation of in vivo sensors

ABSTRACT

A device, system and method for selectively activating or altering the operational mode of an autonomous in vivo device in response to in vivo conditions. The system includes an in vivo sensing device with a condition tester, and a controller. The in vivo sensing device may be in communication with an external receiver.

FIELD OF THE INVENTION

The present invention relates to the field of in vivo devices. Morespecifically, the present invention relates to a device, system andmethod for selectively activating or altering the operational mode of anin vivo device, for example, in response to in vivo conditions.

BACKGROUND OF THE INVENTION

Certain in vivo devices may be introduced into a body in a locationremote to the area where their sensing, diagnosing or other functionsmay be performed. For example, an in vivo device for imaging areas ofthe small intestine may be introduced into a body through the mouth andpass through the stomach and other parts of the gastrointestinal (GI)tract by way of peristalsis until reaching the small intestine.Similarly, an in vivo device may be introduced into a body wherein thelocation of an area of interest or of a suspected pathology may beunknown or uncertain, thereby necessitating that an in vivo device passfrom its point of introduction and locate the area of pathology whereits sensing functions or other functions may be required for diagnosingpathologies or performing other functions.

In vivo devices such as sensors are generally configured to capturesensory data on a fixed schedule that may be set or programmed into thein vivo sensor before it may be introduced into a body. For example, anin vivo image sensor may be configured to capture images at fixedintervals beginning with the time that it is introduced into the body.Typically, an in vivo sensor may be activated by a doctor or medicalpractitioner who assists in introducing such sensor into the body. Otherin vivo sensors may be activated before ingestion, for example,automatically upon their removal from their original packaging. As aresult, an in vivo sensor introduced to a location in the body that maybe remote from an area of interest or suspected pathology in a body, mayperform its sensing functions or other functions in locations other thanthe area of interests for example where no pathology or suspectedpathology exists. The performance of such superfluous sensing mayinefficiently utilize the power supply, data collection, data transfer(bandwidth), data storage capacity and/or other of the sometimes limitedresource of the in vivo sensor. Redundant data may be required to bereviewed by the physician, increasing the overall review time.

The capturing of data by an in vivo sensor based on a fixed schedule mayresult on the one hand, in superfluous data being collected in areasthat may be of little diagnostic or other interest, and, on the otherhand, in insufficient sensory data being captured of in vivo areas thatmay be of particular diagnostic or other interest. For example, an invivo image capturing system may be programmed to capture in vivo imagesat a rate of, for example, two frames per second. While such framecapture rate may be for example sufficient to generally capture adequateimages of most of the small bowel, such frame capture rate may be tooslow to achieve the level of imaging detail that may be required forareas such as the esophagus or other areas.

There is therefore a need for a system and method for allowing anefficient and effective operation of an in vivo device.

SUMMARY OF THE INVENTION

There is thus provided according to one embodiment of the invention, asystem for in vivo sensing including for example an in vivo sensingdevice with a condition tester, and a controller. The condition sensormay for example be operatively linked with the controller so as tocontrol for example an operational mode of the in vivo sensing device.

It is also provided according to an embodiment of the invention, amethod for controlling, for example an in vivo imaging device by, forexample, sensing a condition in vivo and triggering an event in the invivo imaging device based on the sensing.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description taken in conjunction with theappended drawings in which:

FIG. 1A is a schematic illustration of an in vivo device that may beused in accordance with an embodiment of the present invention;

FIG. 1B is a schematic illustration of a receiver in accordance with anembodiment of the present invention;

FIG. 1C is a schematic illustration of a data processor in accordancewith an embodiment of the present invention;

FIG. 2 is a schematic illustration of an in vivo device with a conditionsensitive, color-changing material in accordance with an embodiment ofthe present invention;

FIG. 3 is a schematic illustration of a device with two image sensors inaccordance with an embodiment of the present invention;

FIG. 4 is a schematic illustration of a condition tester in the form ofa coating in accordance with an embodiment of the present invention;

FIGS. 5A and 5B are schematic illustrations of a floatable deviceaccording to an embodiment of the invention;

FIG. 6 sets forth a flow chart of the operation of a controller inaccordance with an embodiment of the present invention;

FIG. 7 sets forth a flow chart of the operation of a device inaccordance with an embodiment of the present invention;

FIG. 8 sets forth a schematic diagram of a temperature triggered circuitin accordance with an embodiment of the current invention;

FIG. 9 is a chart depicting a change in mode based on a pH trigger inaccordance with an embodiment of the current invention; and

FIG. 10 is a chart depicting a change in mode initiated by a pH triggerand combined with a timed delay in accordance with an embodiment of thecurrent invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, various aspects of the present inventionwill be described. For purposes of explanation, specific configurationsand details are set forth in order to provide a thorough understandingof the present invention. However, it will also be appreciated by oneskilled in the art that the present invention may be practiced withoutthe specific details presented herein. Furthermore, well-known featuresmay be omitted or simplified in order not to obscure the presentinvention.

According to some embodiments of the invention, a system, method anddevice are provided for triggering an event such as, for example,activating or altering the operational mode of an in vivo device and/ora receiving (and/or processing, and/or reviewing) unit, typicallylocated outside a patient's body, in response to in vivo conditions asmay be detected by an in vivo condition tester. Such activating,deactivating or altering operational modes may include for example,activating or deactivating one or more components of the in vivo deviceand/or the receiving unit, increasing or decreasing the powerconsumption, increasing or decreasing the level of illumination,increasing or decreasing the rate of sensing, such as, for example,increasing the data capture rate from, for example, 2 images per secondto for example, 14 images per second, or altering the sensing parameterssuch as, for example, in the case of an in vivo image sensor, increasingor decreasing the illumination intensity of the light sources oraltering the image plane of the image sensor. Other operational modesmay be changed and other data capture rates may be used. In certainembodiments, more than one in vivo sensor may be included in a singledevice. A change in the operational mode of the device may in suchembodiments include activating or deactivating one or both of suchsensors or alternating the activation of such more than one sensor. Forexample, an in vivo image sensor may include two image sensors. A changein operational mode may in such example mean activating or deactivatingone or both of such image sensors, or alternating the activation of suchimage sensors. In other embodiments, one in vivo device may activate ordeactivate one or more components in second in vivo device.Communication between two or more in vivo devices may be for examplethrough one or more external receivers or may be through for exampledirect communication between one or more in vivo devices.

In certain embodiments changes in the operational mode may for exampleinclude changes in the methods or procedures of processing sensory dataobtained, and optionally transmitted, from the in vivo device. Forexample, sensory data such as images or ultrasound readings fromendo-luminal areas that have villi may return distorted images as aresult of the irregular surfaces of the villi. In certain cases, suchdistortions may be corrected through changes in the methods ofprocessing of the sensory data by the data processor. For example,specific image processing algorithms may be activated. According to oneembodiment methods of processing sensory data may be executed, forexample, in an external receiving unit. In another embodiment the changemay be in the mode of the data presentation (reviewing mode), e.g.presentation of the images in double image vs. single image mode.

The invention according to certain embodiments, comprises an in vivodevice such as, for example, an in vivo image capture system, an in vivocondition tester such as, for example, any of an in vivo pH tester,blood detector, thermometer, pressure tester, spectral analytic imagesensor, biosensor for biosensing, accelerometer, or motion detector, anda controller for linking the condition tester with the in vivo deviceand for signaling the change to be made in the operational mode of thein vivo device. Other condition testers may also be used as well as acombination of two or more condition sensor may be used. In oneexemplary embodiment a biosensor may be used to sense, for example,colon specific flora in a colon. In another exemplary embodiment apressure tester may be used to sense, for example, a change in pressure,such as a change in pressure pattern. For example, a drop in pressuremay be sensed by a pressure tester, for example, when the device movesfrom the small intestine to the cecum (at the beginning of the colon).Various signals emitted by the condition tester such as mechanical,electrical, electromagnetic, chemical, or optical signals may also beused.

Embodiments of the present invention may be used with in vivo devicesand recording/receiving and display systems such as various embodimentsdescribed in U.S. Pat. No. 5,604,531, assigned to the common assignee ofthe present application and incorporated herein by reference, and/orPublication Number WO 01/65995, also assigned to the common assignee ofthe present application and incorporated herein by reference. Other invivo systems, having other configurations, may be used.

Embodiments of the device may be typically autonomous and typicallyself-contained. For example, the device may be a capsule or other unitswhere all the components are substantially contained within a containeror shell, and where the device does not require any wires or cables to,for example, receive power or transmit information. The device maycommunicate with an external receiving and display system to providedisplay of data, control, or other functions. For example, power may beprovided by an internal battery or a wireless receiving system. Otherembodiments may have other configurations and capabilities. For example,components may be distributed over multiple sites or units. Controlinformation may be received from an external source.

An in vivo imaging system for example, that may be included in aningestible device such as a capsule may capture and transmit images ofthe GI tract while the capsule may pass through the GI lumen. Inaddition to the imaging system, a device such as a capsule may include,for example, an optical system for imaging an area of interest onto theimaging system and a transmitter for transmitting the image output ofthe image sensor. A capsule may pass through the digestive tract andoperate as an autonomous video endoscope. It may image difficult toreach areas of the GI tract, such as the small intestine. Other devicesmay be included, and devices including sensors other than image sensorsmay be used. Configurations other than capsules may also be used.

Reference is made to FIG. 1A, a schematic illustration of an in vivodevice in the form of for example, a swallowable capsule that may beused in accordance with an embodiment of the present invention. Device40 may comprise an image sensor 46, an in vivo optical system 41 forfocusing light reflected back from in vivo areas (not shown) onto imagesensor 46, an illumination source 42, such as one or more light emittingdiodes (LEDs) or other suitable sources, a dome 44 that may be useful,inter alia, for protecting the optical system from body fluids, acircuit or controller 48 for controlling the operational mode, such asfor example settings of the device 40, a condition tester 49 such as forexample, a pH tester or thermometer, an in vivo memory unit 39, an invivo power source 45 such as a set of batteries, an in vivo receiver 43for collecting signals transmitted to device 40, and an in vivotransmitter 47 for transmitting signals and/or image data to a receiver.One or more of in vivo image sensor 46, in vivo illumination source 42,controller 48, in vivo memory unit 39, in vivo transmitter 47, in vivoreceiver 43 and condition tester 49 may in certain embodiments of thepresent invention be operatively connected, for example to/or throughPCB 38, or included or embedded within an application specificintegrated circuit (ASIC) 50. In other embodiments, image sensor 46,controller 48 and condition tester 49 may be operatively linked to eachother without an ASIC 50 or PCB 38 or other connecting means. A wired orwireless connection, such as for example a microwave connection or othersuitable connections may be used between elements in the capsule. Suchan ASIC 50 may provide control for the capsule. Alternatively, anothercomponent such as transmitter 47 may provide such control.

In certain embodiments, image sensor 46 may be a CCD or a CMOS imagesensor that may have arrays of various typically color pixels. Othersuitable image sensors or no image sensors may be used. In oneembodiment of the invention, image sensor 46 may also function as acondition tester. For example, an image sensor may be used to detect forexample, blood vessel structures typically found in colon, or villistructures typically found in small intestine. Detection of suchstructures, detection of lack of such structures, or detection of otherstructures or colors such as for example color specific to content inthe intestine may be used to trigger an event in the in vivo device.Other suitable structures or colors detected may be used as a trigger.Detection, according to an embodiment of the invention, could be aidedby appropriate image processing algorithms and/or suitable software.

In other configurations of device 40, components such as capsulereceiver 43, power source 45, in vivo memory unit 39 or other units maybe omitted.

Typically, device 40 is swallowed by a patient and traverses a patient'sGI tract. Other suitable body lumens or cavities may be imaged orexamined.

Reference is now made to FIG. 1B, a schematic illustration of anexternal receiver 12 in accordance with an embodiment of the presentinvention. External receiver 12 may typically be located outside thepatient's body and may receive and/or record and/or process the datatransmitted from device 40. External receiver 12 may typically include areceiver antenna (or antenna array) 15, for receiving image and otherdata from device 40 and stored in for example storage unit 16.Typically, external receiver 12 may be portable, and may be worn on thepatient's body during recording of the images.

External receiver 12 may also be equipped with processing unit 11, suchas for example signal processing unit and/or control software or forexample a control mechanism or circuit emulating such functionality thatmay control for example, evaluate and respond to signals transmitted bydevice 40. External receiver 12 may also include a transmitter andreceiver transmitter 17 that may enable external receiver 12 to transmitsignals such as control signals to device 40. External receiver 12 mayalso include a user interface (not shown) that may inter alia provideindications to a user or patient as to changes made in the operationalmode of a device. For example, passage of a capsule through the stomachmay be identified by changes detected in pH levels that may for exampletrigger a change in the operational mode of a sensor such as an imagesensor. A patient may be signaled via a user interface that such modechange is being made and prompted to take certain actions such as forexample, changing positions (such as for example, changing from asitting position to a reclining position), ingesting a laxative, orcertain liquids, etc.

Reference is now made to FIG. 1C, a schematic illustration of a dataprocessor in accordance with an embodiment of the present invention.Preferably, data processor 14, data processor storage unit 19 andmonitor 18 are part of a personal computer or workstation that mayinclude standard components such as a processor 13, a memory (such asstorage unit 19, or other memory), a disk drive, and input-outputdevices. Alternate configurations are possible. In alternateembodiments, the data reception and storage components may be of anotherconfiguration. Further, image and other data may be received in othermanners, by other sets of components. Typically, in operation, imagedata is transferred from external receiver 12 to data processor 14,which, in conjunction with processor 13, storage 19, and software,stores, possibly processes, and displays the image data on monitor 18.Other systems and methods of storing and/or displaying collected imagedata may be used. In other embodiments, processing of data can beperformed by components within the external receiver 12.

Typically, device 40 may capture an image and transmit the image byusing, for example, radio frequencies, to receiver antenna(s) 15. Inalternate embodiments external receiver 12 is an integral part of dataprocessor 14. Typically, the image data recorded and transmitted isdigital color image data, although in alternate embodiments othersuitable image formats (e.g., black and white image data, infrared imagedata, etc.) may be used. In one embodiment, each frame of image data mayinclude 256 rows of 256 pixels each, each pixel including data for colorand brightness, according to known methods. For example, color may berepresented in each pixel by a mosaic of four sub-pixels, each sub-pixelcorresponding to primaries such as red, green, or blue (where oneprimary is represented twice). The brightness of each sub-pixel may berecorded by, for example, a one byte (i.e., 0-255) brightness value.Other data suitable formats may be used. In one embodiment, image sensor46 may capture or transmitter 47 may transmit image or other data in adiluted mode, capturing or transmitting for example, 16 rows of 16pixels each.

In an embodiment, in vivo transmitter 47 may include at least amodulator (not shown) for modulating the image signal from the imagesensor 46, a radio frequency (RF) amplifier (not shown), and animpedance matcher (not shown). The modulator may convert the input imagesignal that may have for example, a cutoff frequency f_(c) of less than5 MHz to an RF signal having a carrier frequency f_(r), that maytypically be in the range of 1 GHz. The carrier frequency may be inother bands, e.g. a 400 MHz band. The modulated RF signal may typicallyhave an appropriate bandwidth of f_(t). The impedance matcher may matchthe impedance of the circuit to that of the antenna. Other suitabletransmitters or arrangements of transmitter components may be used,utilizing different signal formats and frequency ranges. In oneembodiment of device 40, transmission may occur at a frequency forexample of 434 MHz, using for example Phase Shift Keying (PSK) or MSK(Minimal Shift Keying). In alternate embodiments, other suitabletransmission frequencies and methods, such as for example AM or FM maybe used.

External receiver 12 may detect a signal having the carrier frequencyf_(r) and the bandwidth f_(c) such as described hereinabove. Externalreceiver 12 may be similar to those found in televisions or it may beone similar to those described on pages 244-245 of the book “BiomedicalTelemetry” by R. Stewart McKay and published by John Wiley and Sons,1970. The receiver may be digital or analog. In alternate embodiments,other receivers, responding to other types of signals, may be used.

In certain embodiments, condition tester 49 may be an in vivo pH tester,as is well known in the art, for example a pH tester using thetechnology used in known pH measuring capsules. Such pH tester mayutilize as electrodes an external ring electrode made of antimony andthe zinc-silver chloride electrode of the battery that powers thetester. A saline solution such as for example, a 0.9% physiologic salinesolution may be introduced into the electrode chamber immediately priorto the testing. The potential difference that develops between the twoelectrodes and that depends on the pH may be applied to a transistor asa frequency-determining measuring voltage.

Other pH testers, such as ion selective field effect transistors(ISFET), may also be used as condition tester 49 to evaluate pH in areasadjacent to the location of the device 40. ISFET sensor chips that maybe used for in vivo pH detection are known in the art as may bedescribed, for example, in Wang, L., Integrated Micro-Instrumentationfor Dynamic Monitoring of the Gastro-Intestinal Tract, as presented atthe IEEE Instrumentation and Measurement Technology Conference, May2002, retrieved on Oct. 15, 2002 from the Internet: <URL:http://www.see.ac.uk/naa.publications.html>. Other suitable pH testersmay also be used. An ISFET sensor serving as condition tester 49 may beoperatively connected to ASIC 50 or otherwise may be connected directlyto image sensor 46. In a typical embodiment, an ISFET sensor serving ascondition tester 49 may be situated adjacent to the outer wall of thedevice 40 so as to maximize the exposure of such condition tester 49 tothe in vivo conditions outside of such wall of device 40.

In some embodiments, controller 48 may be substituted or complimented byan external controller located out of the body. For example the externalcontroller may be an integral part of processor 11. In such embodiments,triggering may be external triggering. Condition tester 49 may transmita signal to in vivo transmitter 47 that transmits such signals toreceiver antenna(s) 15. External receiver 12 may process such signalsand transmit back triggering signal such as instructions by way ofreceiver transmitter 17 to in vivo receiver 43. In vivo receiver 43 maythen direct a change in the mode of operation of device 40. In someembodiments, external receiver 12 may be capable of overriding orinitiating a change in the mode of operation of device 40 in response toa signal that is input to receiver by medical personnel.

A condition tester such as for example, a pressure sensor may use astrain gauge as a condition detector, such as for example, a thin foil,typically a semiconductor or a piezoelectric material. Such strain gaugemay accept power through a wire and provide a variable strain signal onsuch wire.

In other embodiments, condition tester 49 may take the form of acondition sensitive, color-changing material. Reference is now made toFIG. 2, which is a schematic illustration of an in vivo sensor with acondition sensitive, color-changing material 202 in accordance with anembodiment of the present invention. Material 202 may be temperaturesensitive. “Temperature-sensitive” in the context of the presentinvention may be defined as reactive to a change in temperature. Thistemperature change may include a range of temperatures or a change froma reference temperature to another temperature. In other embodiments,material 202 may be pressure-sensitive, pH sensitive or sensitive to thepresence of certain substances such as for example, blood, withcolor-changing characteristics varying with changes in such conditions.Thus, different properties within the environment of the body lumen canbe measured in a manner similar to the one described for temperaturehereinbelow. For example, a pH condition tester may use litmus paper asa color-changing material 202, and a blood detector may use apolyelectrolyte as a color-changing material 202, as known in the art.

In an embodiment, the temperature-sensitive, color-changing material 202may be a Thermotropic Liquid Crystal (TLC) paint or coating, such as areoffered by Hallcrest, Inc. of Glenview, Ill. The TLCs, that may, forexample, be cholesteric (including sterol-derived chemicals) or chiralnematic (including non-sterol based chemicals) liquid crystals, or acombination of the two, provide color changes in response to temperaturechanges. These color changes may be reversible or hysteretic. In certainembodiments that include materials 202 that may be capable of reversiblecolor changes, controller 48 may be programmed to reverse or furtheralter the operational mode changes in image sensor 46 in the event thata condition tester ceases to detect the changed color of material 202.

The TLC can be used in several forms according to several embodiments,including but not limited to paints, microencapsulated coatings andslurries, TLC coated polyester sheets, and unsealed films.

As shown in FIG. 2, temperature-sensitive color-changing material 202may be placed on the inside of capsule 200, with color-changing portionsfacing inwards. By placing material 202 on the inside of the capsule,potential problems associated with the biocompatibility and theresilience of material 202 in light of bodily fluids and pH changes maybe avoided. However, it should be apparent that color-changing materialmay also be placed on the outside of capsule 200 where it may be incontact with bodily fluids. Such contact between material 202 and bodilyfluids may facilitate testing of such bodily fluids for reactions withmaterial 202. In certain embodiments, it may be necessary to achievecontact between bodily fluids and material 202. The attachment orplacement of material 202 can be accomplished in several ways. Forexample, material 202 may be in the form of paint, and may be paintedonto the capsule. In another embodiment, material 202 may be attachedonto the capsule with adhesive. In a further embodiment, material 202may be sprayed onto the dome 44 as a coating. In yet a furtherembodiment, material 202 may be enclosed in a semi-permeable membrane incontact with bodily fluids.

In the course of the function of capsule 200, light from a light source204 may be directed towards material 202. Light source 204 may includeone or several components, preferably light emitting diodes (LEDs) thatmay be placed in various locations within capsule 200. Light source 204may also be used as or provided by illumination source 42 shown in FIG.1, to illuminate the environment being imaged (outside of the capsule),or a separate illumination source 204 may be included for that purpose.

Changes in in vivo conditions, such as, for example, changes intemperature, pH, pressure, the presence of blood and the like (dependingon the nature of material 202), may in certain embodiments cause variousmaterials that can be used as color-changing material 202, to changecolor. Image sensor 46 detects the appearance of the new color whenlight from light source 204 is reflected back from material 202 ontoimage sensor 46. Referring to FIG. 2, such detection of changes in colormay in certain embodiments be performed by a subgroup of pixels 206included in the pixel array of image sensor 46. In one embodiment of theinvention, pixel array of image sensor may have one subgroup of pixelsthat are sensitive to a first range of wavelengths e.g., colors andanother subgroup of pixels sensitive to second range of wavelengths,e.g., colors. In some embodiments such one subgroup of pixels, orspecific pixels may be positioned on the pixel array of image sensor 46to be exposed to light reflected back from material 202 considering theangle of incidence 208 and angle or return 208′ of the light directedonto and reflected back from material 202. Similarly, in certainembodiments, such subgroup of pixels 206 may be sensitive to a specifiedrange of colors that appear on material 202 once the designated in vivoenvironmental condition may be detected. In an alternative embodimentspecial photodiode(s) may be used in addition to or in place of asubgroup of pixels 206 to detect color changes.

When a designated change in color of material 202 is detected by asubgroup of pixels 206, a signal may be sent to controller 48 by such asubgroup of pixels 206 or by another component operatively connected toa subgroup of pixels 206. In certain embodiments, a subgroup of pixels206 may be replaced or supplemented by a spectral analyzer that iscapable of detecting color changes in material 202. Othercolor-sensitive detectors may also be used. Such detection or processingmay also be aided or performed by a processor or circuitry located inASIC 50, external receiver 12 or data processor 14.

In certain embodiments, a range of color sensitive pixels, some of whichmay be sensitive to the various colors that can appear on material 202may be situated on pixel array 210 of image sensor 46. Signals producedby each of such specific pixels 206 may vary depending on the colorappearing on material 202. Controller 48 may detect and differentiatebetween such various signals, for example by utilizing appropriate imageprocessing algorithms, and issue instructions to a sensor in response toeach thereof. According to one embodiment a change of color may bedetected in the in vivo environment that is being imaged. For example, aspot of bleeding may appear in a certain image. The change of color,that may indicate, for example, pathology in the GI tract, may berecognized by known methods. For example, controller 48 or dataprocessor 14 may generate a probability indication of presence ofcolorimetric abnormalities on comparison of color content of the imagesand at least one reference value, for example, as described in PCTpublication WO 02/073507, published on 19 Sep., 2002, that is assignedto the common assignee of the present invention. According to someembodiments, once a color change may be detected the controller 48 ordata processor 14 may initiate a change in the mode of operation ofdevice 40, of the external receiver 12, of both or of any othercomponent or combination of components of the system. In otherembodiments, a photodiode maybe used to detect changes in material 202.Such photodiode may in certain embodiments be connected to an amplifierthat may be further connected to a comparator. A mode change may therebybe triggered by analog rather than digital electronics.

In one embodiment of the invention, one or more photodiodes may be usedto detect light, such as for example, visible light, IR light, or otherranges of light illuminated for example externally through the skintoward an in vivo area of interest. A photodiode or other lightdetecting unit, for example incorporated in an in vivo device may senseillumination when approaching for example toward such area of interest.Such detection may trigger a change in operational mode. Other suitablesignals besides light may be used to penetrate the skin or other tissueand other suitable detection units may be used to pick up penetratedsignal in vivo. For example, an acoustic signal may be used.

In an embodiment, capsule 200 may operate in a low power consumptionmode until a color change in material 202 may be detected. For example,until such color change may be detected, light sources 204 may be set toilluminate once every second, thereby consuming less power than used bythe overall capsule 200 during full operation that might in certainembodiments illuminate several times a second or more. In response to asignal that may be detected from specific pixels 206, controller 48 (oranother component located in capsule 200, external receiver 12 or dataprocessor 14) may alter the mode of operation of capsule 200 or of anyother component of the system. For example, in certain embodiments, anyor both of light source 204 and image sensor 46 may be directed toincrease the rate of capture of images in order to more fully image theendo-luminal vicinity wherein a specific condition may have beendetected. Controller 48 may direct other activations or alterations inthe mode or operation of capsule 200. In other embodiments, the responseof controller 48 to signals from specific pixels 206, may be, forexample, any of turning on the image sensor 46 that may theretofore havebeen inactive, changing mode of image sensor or transmitter, collectingsamples of in vivo liquids or other materials, releasing encapsulateddrugs that were held in capsule 200 or performing other functions.

In some embodiments, the pixels receiving the color indication may be,for example, the regular pixels of image sensor 46. Post processingcircuitry or software located in capsule 200, external receiver 12 ordata processor 14 may analyze the signals from the set of pixels (setbeing understood to include one unit) and make a mode changedetermination therefrom.

Other embodiments besides calorimetric changes may include, for example,temperature measurement using devices such as thermistors (located in acapsule for example as a discrete component or as part of ASIC) or usingpH electrodes, and other embodiments.

Reference is now made to FIG. 3 that is a schematic illustration of acapsule 300 with two image sensors in accordance with an embodiment ofthe present invention. Capsule 300 has one image sensor 302 at one endof capsule 300 and a second image sensor 304 at another end of capsule300. In an embodiment of the present invention, condition tester such asa color-changing material 202 such as those described in FIG. 2 may beinstalled proximate to image sensor 302, and such image sensor 302 mayin such embodiment have specific pixels 206 similar to those describedabove for detecting color changes in material 202. When a change incolor of material 202 is detected by image sensor 302, a signal of suchchange is sent to controller 48 of capsule 300. Controller 48 may insuch embodiment alter the operational mode, such as for example byactivating a component, for example the image sensor 304 of capsule 300.For example, the operational mode of both or either of image sensors 302and 304 may be changed. Such a mode change may, for example, increasethe number of images to be captured of such area or alter theorientation of images captured or differential activation of either oneor both image sensors may be affected in response to a signal, or othermode changes discussed herein.

In certain embodiments, controller 48 may be configured to delay issuingoperational mode change orders to until more than one signal fromcondition detector 49 may have been received. In an embodiment of thepresent invention, controller 48 may be configured with a delaymechanism in the form of for example a counter 51 that causes controller48 to delay activating or altering the operational mode of image sensor304 until several signals from condition tester 202 may have beenreceived, or until signals signifying that a certain condition existsmay be received over the course of a certain period of time. Suchactivation may, for example, reduce the chance that a false reading orfleeting condition activates image sensor 304, or may provide“debouncing” in case conditions may change in a variable manner betweenone relatively steady state and another. For example, in one embodiment,capsule 300 may operate in a first mode (e.g., low power consumption, orat a first frame capture rate) in the mouth and esophagus, where the pHis generally approximately 7-8. When capsule 300 reaches the stomach,where the pH is typically about 2, a pH detector on or within capsule300 may detect a change in pH, and the operational mode may change, forexample to a different power consumption, or a different frame capturerate. Later, when capsule 300 reaches the small intestine, capsule 300may detect a change in pH to, for example 7-8, and the operational modemay change again. A change in pH may cause alteration in the operationalmode only if received for, for example, one minute (other suitable timeperiods may be used). Other methods of debouncing or guarding againstfleeting conditions may be used.

Controller 48 may in certain embodiments be a software controllerembedded into ASIC 50. In other embodiments, controller 48 may be asimple switch or circuit connected to for example a condition testersuch as a thermistor 800. The controller may include, for example, anamplifier 802 and a comparator 804, comparing the measured signal tosome pre-defined threshold 806, as are depicted forth, for example, inFIG. 8. Such switch or circuit may in certain embodiments power on ortrigger the activation of ASIC 50 when the proper condition may bedetected. In other embodiments, such switch or circuit may signal ASIC50 to, for example, begin operation or change the mode of operation ofthe sensor.

In a further embodiment, the switch from one condition and then back toanother may be the trigger for a mode change. For example, in case ahigh pH is detected for a period, then a low pH, then again a high pH,the mode change may occur only on the third condition change. Othersuitable signals or series of signals may be used to trigger othersuitable functionalities. Further, altering the mode based on detectionof a condition change may be combined with, for example, a delay. Forexample, capsule 300 may wait, for example, one hour after detecting acondition change to effect a mode change. FIG. 4 is a schematicillustration of a condition tester in the form of a coating inaccordance with an embodiment of the present invention. In suchembodiment, a portion of capsule 400 may be coated with one or morelayers of a dissolvable material 402. Each layer of dissolvable material402 may be comprised of varying substances that dissolve at varyingrates or when exposed to specific materials or environments. Forexample, a first, outer layer 404 of dissolvable material may be pHsensitive and dissolve when exposed to the acidic environment of thestomach, and may expose certain components such as for example switches412, sensors 408 or drug compartment 410 with an opening, while capsule400 may be in a specified site such as for example, the stomach. Asecond inner layer 406 may for example, dissolve in the more basicenvironment of the small intestine and may activate other sensors orrelease other encapsulated drugs. Other materials that may be sensitiveto elapsed time and dissolve in accordance with a specific period oftime after introduction to the GI tract may also be possible as a meansof delaying activation of certain functions of capsule 400. An exampleof dissolvable materials that may be used as such coatings includestarches, such as gelatinous materials, waxes, biodegradable plastics,and other known biodegradable materials. Other suitable dissolvablematerials with other characteristics may also be used.

Dissolvable material 402 may cover any or all of a sensor 408, such asfor example, a pH sensor, a switch 412, such as for example a switchthat turns on an image sensor, an encapsulated drug compartment 410 thatreleases its contents or a sampling inlet 414 that lets surroundingfluids enter a compartment where such fluids may be sampled, captured orevaluated by a sensor. When dissolvable material 402 dissolves, sensor408 may be exposed, switch 412 may be activated, sampling inlet 414 maybe opened or an encapsulated drug compartment 410 may release itscontents into the surrounding area. In other embodiments, the dissolvingof dissolvable material 402 may facilitate contact between electricalleads that had theretofore been separated, such contact may signal achange in operational mode. According to another embodiment a magnet maybe held in the vicinity of the capsule 400 such that it affects theON/OFF status of the capsule. In some embodiments the magnet may beembedded in a dissolvable coating, such as dissolvable material 402,such that while the coating is intact, the capsule is OFF. When thecoating dissolves, for example, in response to environmental pH, themagnet may be freed and may become dissociated from the capsule allowingthe capsule to be ON. In other embodiments other suitable environmentaltriggers may cause the dissolving of coatings.

Another embodiment is schematically illustrated in FIGS. 5A and 5B. Inthis embodiment an imaging capsule 500 may be a floatable capsule, forexample, a capsule having a specific gravity of less than 1. A floatablecapsule is described, for example, in Publication Number WO 02/095351,published on Nov. 28, 2002 assigned to the common assignee of thepresent inventions and is hereby incorporated in its entirety byreference. Such a capsule may be advantageous for passage throughportions of a voluminous cavity, such as the stomach and/or largeintestine. In other portions of voluminous cavities (e.g., thedescending portion of the large intestine) a floatable capsule may bedelayed rather than advanced. Thus, a floatable capsule may benefit fromhaving the option of loosing its floatation characteristics at a givenpoint during its passage through the GI tract, for example, while in thelarge intestine.

According to one embodiment, a capsule may have a fluid chamber such asfor example a floatation compartment 502 that may be filled with afluid, a gas, or other suitable material that is lighter than theendo-luminal fluid, for example, air. In certain embodiments, floatationcompartment may be as small as 5% of the volume of capsule 500. Othersuitable volumes may be used. The floatation compartment 502 may have avalve 504 keeping the compartment 502 closed and the capsule 500floating. Upon triggering, valve 504 may be opened (see FIG. 5B).Floatation compartment 502 may then be filled with endo-luminal liquid,raising the specific gravity of capsule 500 and rendering capsule 500non-floating. As such the floatation mode of a capsule may be altered.

A number of mechanisms for opening valve 504 may be implemented, suchas, electronic, mechanical or chemically based mechanisms. For exampleinstant heating (requiring only a small amount of battery energy) may beapplied, melting material of valve 504. The signal for effecting thechange may be as described above.

FIG. 6 sets forth a flow chart of the operation of a controller 48 inaccordance with an embodiment of the present invention. Such controllermay in an embodiment be a software controller in the form of logicprogrammed into, for example ASIC 50, controller 48, external receiver12 or other suitable components. Such software controller may have aflag to indicate the operational mode to which a sensor is set. Settingsof such flag may be 0 or 1 for on or off, or other suitable settings toindicate other settings to which a sensor may then be operating.Software controller may also include a counter that may in certainembodiments count signals received from condition tester 49 indicatingthe detection of the conditions to be tested by condition tester 49.Software controller may also be operatively linked to an operationactivator of an in vivo component such as image sensor 46 that controlsthe operation of such sensor. For example, operation activator may be aninternal clock that controls the timing of the image capture rate ofimage sensor 46 or the operation of light source 204.

In its initial state 602, the flag of software controller may be set to0, the counter may be set to 0 and the activator may be set to 0. Insuch settings, image sensor 46 may not be capturing images or may be insome other reduced mode of operation. In step 604, condition tester 49may detect a changed condition in the in vivo area surrounding capsule40 and may signal software controller 48 as to such changed condition.Such signal increments counter to 1 Step 604 may be repeated bycondition tester 49 at periodic intervals that match the sampling rateof condition tester 49. Each signal delivered by condition tester 49that indicates the changed condition may increment the counter by 1(605). Once the counter reaches a designated threshold in step 606, theflag switches to 1 in step 608. Such switch by the flag to 1 switchesthe sensor activator to 1 as in Step 610. The activator may then changethe mode of operation of image sensor 46. Such change may for example bean increase in the frame capture rate of image sensor 46 or any othersuitable change in the operational mode of the sensor.

In certain embodiments, the counter may be decremented each timecondition tester 49 sends a signal to controller 48 that indicates theabsence of an elevated condition, thereby possibly indicating thatconditions may have returned to pre-defined normal levels. Once thecounter may have been decremented below a pre-defined threshold level,the flag may revert to 0 and may reset the activator to its initialsetting so that such sensor may resume the operational mode that was ineffect prior to the change described above, or some other suitableoperational mode.

In other embodiments, condition tester 49 may be, for example, a clocksuch as for example an internal clock embedded into ASIC 50 or otherwiseoperatively connected to image sensor 46. In such case, controller 48may be a component such as for example a switch operatively attached tosuch embedded clock that may turn on once a designated period haselapsed. Such elapsed period may be the estimated time that it takescapsule 300 to pass through the stomach and into the small intestinewhere the desired image capturing may take place. Other periods may alsobe designated depending on where in the GI tract the desired imagecapturing may be designated to begin.

In yet further embodiments, an ingestible capsule may be meant forimaging or otherwise sensing distal portions of the GI tract, such asthe large intestine. A method for economically using an imaging (orother sensing) capsule is provided according to an embodiment of theinvention. FIG. 7 illustrates a method for imaging or otherwise sensingdistal parts of the GI tract according to an embodiment of theinvention. An inactive device such as for example a capsule (e.g., doesnot sample or transmit images or other data) is swallowed (710) by apatient. According to one embodiment the capsule may comprisetemperature sensing capabilities. Any in vivo temperature sensingmechanism, such as those known in the art, may be used. After a capsuleis swallowed a patient may be made to ingest a volume of cold or hotwater (720) at regular intervals. According to one embodiment thepatient may ingest cold or hot water over a period of a few hours (e.g.,3-5 hours), for example, a period in which the capsule has most probablyleft the stomach. According to another embodiment the patient may bemade to ingest a volume of cold or hot water until alerted that thecapsule has left the stomach (further detailed below). While the capsulemay be in the stomach an ingested volume of cold or hot water may causea change of temperature in the stomach environment. Once in the smallintestine, the effect of a cold or hot drink may no longer be felt.According to one embodiment a capsule may be programmed to sense aperiodical change in temperature (700), for example to sense atemperature above or below a certain threshold, at predeterminedintervals. While a temperature change may be sensed at predeterminedintervals, the capsule may be kept inactive (701). If a temperaturechange is not sensed at one predetermined time, the capsule may betriggered (for example, as detailed above) to activate the image sensoror other components (702). Thus, the capsule may begin collecting dataonly after leaving the stomach for example, such that it is closer tothe large intestine thereby saving energy and allowing effective andcomplete action of the capsule in the large intestine.

According to some embodiments activating the capsule may cause a signalto be transmitted (703) to an external receiving unit so as to activatean alert 730 (e.g., a beep or a flashing light), that may alert apatient to start or stop an action for example to stop drinking the coldor hot drink (740). Also, the patient may then be prepared for theexpected imaging or otherwise sensing of the large intestine, forexample, the patient may thus be warned to begin taking a laxative.

Reference is made to FIG. 9 that is a chart depicting a change in modebased on a pH trigger in accordance with an embodiment of the currentinvention. As depicted in FIG. 9, a device may be in a first operationalmode from, for example beginning with the time it is turned on and whileit is for example, in the stomach wherein pH is low. As the device mayleave the stomach, pH may rise. Such rise may set off the pH triggerthat may change the operational mode of the device. Other suitabletriggers may be used as well. Such change may, for example, be acomponent such as for example a switch of the device imaging with twoimage sensors 302 and 304 (as are depicted, for example, in FIG. 3) toimaging with only a first image sensor 302. In such an embodimenteffective viewing of the upper regions of the GI tract may be enabled,by using two image sensors whereas, a power saving mode may then beswitched to in the small intestine where one image sensor may be enoughto provide effective viewing.

Reference is made to FIG. 10 that is a chart depicting a change in modeinitiated by a pH trigger and combined with a timed delay in accordancewith an embodiment of the current invention. As depicted in FIG. 10, adevice may be in a first mode of operation immediately when it isintroduced into a body. The mode of operation may change, such as forexample, going to off or some other inactive state, until a triggeroccurs such as for example a change in pH. Other suitable triggers maybe used as well. The trigger may initiate, for example, a time delayduring which the mode of operation may remain initially unchanged, butduring which the device counts down until the delay ends, whereupon themode change may be implemented. A trigger combined with a time delay maybe useful for example where the large intestine may be the area to beimaged. In such an embodiment, the trigger may be the pH change thatoccurs when the device leaves the stomach. The time delay may be theapproximate time required for the device to traverse the small intestine(e.g., 3-6 hours). Once the device nears the large intestine it maychange modes of operation to image the desired area. In this way, thedevice may preserve its power supply until many hours after it isintroduced into a body and until it reaches the targeted imaging area.Other suitable combinations of time delays and triggers are possible.

It will be appreciated by persons skilled in the art that the presentinvention is not limited by what has been particularly shown anddescribed herein above. Rather the scope of the invention is defined bythe claims.

1. A system for in vivo sensing, said system comprising: an in vivosensing device, said device comprising a condition tester; and acontroller to control an operational mode of said in vivo sensingdevice; wherein said condition tester is operatively linked with saidcontroller.
 2. The system according to claim 1 comprising an imagesensor.
 3. The system according to claim 2 wherein the image sensor isselected from a group consisting of: CCD and CMOS.
 4. The systemaccording to claim 2 wherein the image sensor comprises one subgroup ofpixels said one subgroup being sensitive to a first range of colors, andanother subgroup of pixels, said other subgroup of pixels beingsensitive to a second range of colors.
 5. The system according to claim4 comprising a spectral analyzer.
 6. The system according to claim 1wherein the condition tester is selected from a group consisting of: apH tester, a blood detector, a thermometer, a pressure sensor, abiosensor, a spectral analytic image sensor, an image sensor, and acounter.
 7. The system according to claim 1 wherein the condition testeris to test in vivo conditions.
 8. The system according to claim 1wherein the controller is incorporated in the in vivo sensing device. 9.The system according to claim 1 wherein the controller is an externalcontroller.
 10. The system according to claim 1 wherein the controllercomprises a counter.
 11. The system according to claim 1 wherein thecontroller is selected from a group consisting of: mechanical switch,software, and circuitry.
 12. The system according to claim 1 wherein thecontroller is a circuit, said circuit comprising an amplifier and acomparator.
 13. The system according to claim 12 wherein the conditiontester is a thermistor.
 14. The system according to claim 1 comprisingan in vivo transmitter.
 15. The system according to claim 1 comprisingan in vivo illumination source.
 16. The system according to claim 1comprising a photodiode.
 17. The system according to claim 1 wherein thein vivo sensing device is an autonomous device.
 18. The system accordingto claim 1 wherein the in vivo sensing device is a capsule.
 19. Thesystem according to claim 1 wherein the in vivo sensing device comprisesan ASIC wherein said ASIC is operatively connected to a component of thein vivo sensing device.
 20. The system according to claim 19 wherein thecomponent is selected from the group consisting of: an in vivotransmitter, an in vivo illumination source, an in vivo power source, acontroller, an in vivo image sensor, a condition tester, an in vivoreceiver, and an ASIC wherein said ASIC is operatively connected to thein vivo receiver.
 21. The system according to claim 19 wherein thecontroller is an integral part of the ASIC.
 22. The system according toclaim 1 comprising an in vivo receiver.
 23. The system according toclaim 1 comprising an external receiver.
 24. The system according toclaim 1 wherein said external receiver includes a processing unit and astorage unit.
 25. The system according to claim 1 comprising a monitorand a data processor.
 26. The system according to claim 25 wherein saiddata processor comprises a storage unit and a processor.
 27. The systemaccording to claim 1 wherein the condition tester includes acolor-changing material.
 28. The system according to claim 27 whereinthe color-changing material is selected from a group including:temperature sensitive material, pH sensitive material, and a bloodsensitive material.
 29. The system according to claim 1 wherein thecondition tester includes a layer of pH sensitive and/or time sensitivedissolvable material.
 30. The system according to claim 1 wherein the invivo sensing device comprises a compartment coated with a pH sensitiveand/or time sensitive dissolvable material.
 31. The system according toclaim 1 wherein the in vivo sensing device comprises a sampling inletcoated with a pH sensitive and/or time sensitive dissolvable material.32. The system according to claim 1 wherein the in vivo sensing devicecomprises a switch coated with a pH sensitive and/or time sensitivedissolvable material.
 33. A method for controlling an in vivo imagingdevice said method comprising: sensing a condition in vivo; andtriggering an event in said in vivo imaging device based on saidsensing.
 34. The method according to claim 33 wherein sensing acondition in vivo is selected from a group consisting of: time sensing,pH sensing, temperature sensing, pressure sensing, blood sensing, andbiosensing.
 35. The method according to claim 33 wherein the triggeringis by a controller.
 36. The method according to claim 33 wherein thetriggering is by an external receiver.
 37. The method according to claim33 wherein the event comprises a change in an operational mode of the invivo imaging device.
 38. The method according to claim 37 wherein thechange in operational mode is selected from a group consisting of:activating a sensor, deactivating a sensor, altering data capture rate;altering signal format and frequency range of transmission; alteringprocessing of sensory data; altering frame capture rate of an in vivoimage sensor, altering illumination intensity, altering image plane ofan in vivo image sensor, activating in vivo sample collection, releasinga drug, altering power consumption mode, and altering floatation mode.39. The method according to claim 33 comprising delaying triggering ofan event.
 40. The method according to claim 33 comprising ingesting avolume of cold or hot water.
 41. The method according to claim 33wherein the triggering is by a pH sensitive and/or time sensitivedissolvable material.